Outside AC Unit Running But Inside is Not? Not Blowing Air FIX!

Updated: | Author: Brad Javernick | Affiliate links may be present.

Especially in those hot summer months, a good AC unit can be a lifesaver! That’s why when your outdoor AC unit is running but the inside is not, or no cool air is coming through the vents, frustration is sure to follow.

But fear not! There are a few common issues that usually lead to this particular issue and they can usually be resolved pretty easily. Read on to learn what could be going wrong with your AC and how to fix it quick!

When your outside AC is running but the inside unit is not, always check the filter first! If it is old, it should be cleaned or replaced. Next check that the fan is working properly. Ensure that the blades can spin freely and replace the capacitor if needed. Frozen condenser coils could also be to blame. To fix this, defrost the unit.

Always Check the Filter First

If your outdoor AC unit is running but inside it is not, the first thing you should always check is the filter. Especially if you forget to clean or replace it as often as you should. It’s recommended to do this every 3 months or so, especially with constant use.

If your filter is too dirty, all of the dust and debris that’s accumulated can restrict the airflow and lead to a variety of issues. This is why it is so important to check on it regularly.

Remove the filter from the outdoor unit to see how dirty it looks. If it is a reusable filter, wash it off with some warm water and soap before letting it dry completely and reinserting. If it is a single-use filter, check the size and buy a replacement.

With any luck, the AC should be back to working properly and cool air should be flowing in your home immediately after restoring the clean filter.

Broken Fan

When you’ve checked your filter and it definitely isn’t the problem, the next thing to check is the fan. You can easily see if the fan blades are spinning or not when the unit is on, or listen for the sound of the fan if the blades aren’t visible.

Even when you can hear the other components of the outside AC unit running, if the fan is not spinning this will affect airflow and cooling in your home.

If you’re dealing with a broken fan, the good news is that this is actually a relatively simple and cheap problem to fix! This can be fixed much easier than issues with many of the other AC components.

Check for Something Blocking the Blades

The first thing you should do is attempt to move the blades of the fan yourself. Try nudging the blades through the grates using a stick or screwdriver – keep your fingers safe! This will help you figure out if there is any debris physically blocking the blades, which you can then remove.

Sometimes even the act of nudging the fan blades can be enough to kick start the fan again. Then your AC should go back to working normally.

However, if the blades are spinning smoothing when you nudge them but the fan still won’t start, there is probably an issue with the capacitor. The capacitor is the component that supplies power to the fan and it could be shut off or overloaded.

How to Replace a Capacitor

You can call an HVAC specialist to come in and quickly replace the capacitor. If you have experience working with electrical systems, you can also replace it by yourself to save some money.

Before even opening your AC unit to inspect it visually, be sure to disconnect the entire thing from power. Also, it is a good idea to wear rubber work gloves to protect from electrical shocks.

After taking these precautions, open up the panel on your AC unit where it is connected to the power source. Here you should find the capacitor which looks like a metal canister.

You can test the capacitor for capacitance first if you have the proper tools, or look for the specifications and go buy a replacement.

Before removing the old capacitor, be sure to ground it to get rid of any remaining electrical charge. Then you can attach the new capacitor, close up the panel, and switch your (now hopefully repaired) AC back on!

Frozen AC Evaporator

When your fan and filter seem to be doing their jobs but there is still no cold air coming through your vents, your AC evaporator could be frozen over. This problem is very easy to visually check for. Simply remove the side panel of your outdoor unit and look for any ice on the evaporator coils.

If you find ice, the next step is to completely defrost the unit. Do this by turning it off and leaving it to sit until the ice is completely gone and the coils have had time to dry off. On a hot day, this shouldn’t take too long. If you’re in a rush, you can even try to speed up the process by blowing hot air directly on the coils with a hairdryer.

To prevent this from happening again in the future make sure your filter is clean and replaced regularly and that your thermostat isn’t set too low.

If the issue keeps recurring anyway, a refrigerant leak might be to blame. If you suspect this is the case, call in an HVAC specialist to take a look.

Blockage in the Air Duct

 

The final possible problem that could cause your AC not to work inside although the outdoor unit is working is a blocked air duct. Especially when you notice no airflow through the vents, warm or cool, or if the issue is only with certain vents in your home.

This is pretty rare, but something large enough stuck inside of the air ducts can restrict or completely block the airflow into your home. Unfortunately, this can be trickier to diagnose than the other potential causes on this list.

Try removing the vents and using a flashlight to visually inspect the ducts for any blockages. Since you can only see so far, this might not be enough to get to the root of the issue.

If you can’t find any blockage yourself but still feel like this might be your problem, call in an HVAC specialist to investigate further.

Final Thoughts

Using the tips above you can hopefully get your AC working in your home and get the cool air flowing! If all else fails, calling an HVAC specialist is your best bet to finding and fixing the source of your troubles.

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About Brad Javernick

Brad is a licensed home inspector and the editor of Home Oomph. He's a massive DIYer, and loves to take on new home renovation projects!

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